Top 7 solar myths debunked
For one reason or another, there’s a vast amount of misinformation online about disadvantages or problems with solar panels and renewable energy in general. Additionally, there are some very misleading claims about solar panels being toxic, unreliable or not helping reduce emissions. Much of this information originated in the early 2000s when solar was a relatively new technology and still very expensive compared to traditional thermal fossil fuel generation sources such as coal and gas. During this early period, a few of these claims were even true. However, solar technology has advanced rapidly over the last two decades; the cost of solar panels has plummeted, efficiency has increased dramatically, and reliability has improved. With the increasing number of debates about the pros and cons of solar, it’s time to clear up some of these common misleading myths.
Top solar panel myths
Solar panels will not pay for themselves
Solar panels increase the cost of electricity for those without solar
Solar panels don’t work in high temperatures
Solar panels don’t work when it’s cloudy
Solar panels will work during a blackout
Solar panels use more energy to manufacture than they produce
Solar panels are toxic and can’t be recycled
Myth 1. Solar panels will not pay for themselves
If you ask anyone who has solar panels installed, chances are they will have noticed a large reduction in their electricity bill. Not surprisingly, those who notice big savings are also generally more aware of how much energy they use and when they use it. These energy-conscious individuals will often use energy-intensive appliances during the day. Things like dishwashers, washing machines, pool pumps and hot water systems can be set up on timers to maximise the ‘self-use’ of your solar energy. Pre-heating or cooling your home can also be an effective way of increasing self-use rather than feeding excess solar back into the grid for very little return.
The payback period for solar on most homes is 4-6 years in Australia. However, for businesses which operate during the day the payback can be as fast as 3 years. Depending on the upfront cost, this generally offers a return on investment of 8 to 10% per year. This is an extremely good return as the life of a solar panel is generally 20+ years and most manufacturers offer a 15 - 25 year product warranty.
Poorly designed systems or shaded solar panels
Some people who install solar may not notice much of a reduction in electricity costs. This is generally due to most of their electricity consumption occurring during the evening. Another issue is the low grid feed-in tariffs, which provide very little return or rebate for excess solar energy sold back to the grid. This is where simple electronic timers can help maximise the ‘self-use’ of your solar energy, along with running energy-intensive appliances like hot water and pool pumps during the day.
Unfortunately, poor performance is sometimes due to poorly designed systems with excessive shading from trees or rooftop-mounted obstacles. Most solar systems use string solar inverters connected to one or more strings of solar panels - panels linked together in a row. Partial shading of one or more panels in a string reduces power across the whole string. Fortunately, there is a solution. Problems with partial shading (as shown below) can be overcome using DC optimisers or microinverters, which enable each panel to operate independently. These devices help reduce the negative effects of partial shading and can significantly improve the system's performance.
These reasons highlight why you should purchase solar from a reputable solar company and not a door-knocking salesman who will promise you “no more bills” just to make a quick sale.
An example of shading on a string of solar panels from a rooftop air-conditioner. Without panel optimisers the partially shaded solar panels will dramatically reduce the performance of the whole system.
Some larger households may also use a lot of electricity (30 to 50kWh per day) for heating, pools or hot water. In this situation, a typical 6 to 8kW solar array may just be far too small. Larger homes with high consumption will need a larger size solar system, plus owners could try to install more efficient appliances and improve the thermal efficiency of the building to reduce energy costs.
Myth 2. Solar panels increase the cost of electricity for those without solar
This is a common misinterpretation sometimes used to downplay the many benefits of solar. In Australia, there are now over 3 million rooftop solar installations. This huge uptake of solar is due to one simple fact - for most homes and businesses, solar is the only way to reduce electricity costs and become more energy-independent. Unfortunately, not everyone can install rooftop solar panels, which has led to some suggestions that others will have to pay more. In reality, the opposite is true; let me explain…
Solar energy from the millions of homes and businesses significantly reduces the ‘peak demand’ on the electricity network, effectively taking the ‘stress’ off the grid. This is particularly crucial during heatwaves and high temperatures when extra power is drawn from thousands of air conditioners, putting a huge additional load on the grid. In the past, this huge demand was traditionally supported by expensive open-cycle diesel and gas plants. These peaking plants are often only used for these short-term events to reduce peak demand. The high operating cost of these plants can increase wholesale electricity prices by a factor of 10 or more, eventually leading to higher electricity bills for consumers (refer to NEM data). Another issue with relying on thermal generators during heatwaves is the risk of a unit suddenly tripping off due to the increased thermal stress and reduced operating efficiency during hot weather.
Reduced peak demand = lower electricity prices
How does solar help? Hot sunny weather is typically when solar is performing at its best, so additional power can be easily supplied from renewables, as shown in the following chart from data supplied by the Australian National Energy Market operator in OpenNEM. The detailed energy generation data chart below shows so much excess solar energy that the wholesale electricity price has been driven negative! Yes, that effectively means you can get paid to use electricity. However, unfortunately, the vast majority of households don’t purchase electricity at the market price. Electricity retailers and many large industries and manufacturers purchase electricity at wholesale prices, so they can sometimes make a small profit during these negative price events. Households will see reduced electricity prices, but only after lower average wholesale prices have occurred over a full period which is typically one year. This is currently occurring in Australia, with average wholesale prices reducing significantly after the record high prices driven by the global shortage of coal and gas after the Russian invasion and the associated reduction in supply resulting in the energy crisis of 2021. This crisis also highlighted the economic and energy security risks associated with relying primarily on international commodity-priced fuels such as coal and gas.
Total electricity generation in Australia Feb 2024 - OpenNEM data - Rooftop solar accounts for 40% of total generation.
There is so much excess solar energy coming from rooftop solar in cities (especially during hot days when demand is very high) that it is reducing the need for network expansion to cities. However, in some locations where the concentration of homes with solar is very high, the excess solar energy (on days with low demand) can raise the grid voltage, which can, in turn, shut down solar inverters. This is where increasing solar self-use through heating hot water, charging EVs or installing a battery system is very beneficial. This is also part of the reason there are now numerous large-scale battery systems being deployed around Australia and many other countries.
Despite the critics and those opposed to transitioning away from high emissions thermal generation sources, solar has proven to be a remarkably cost-effective and reliable generation source when deployed across a large area. Australia is one of the best examples of this globally, having proven that renewables can power a large megawatt (MW) scale grid using primarily renewables for extended periods of time. As more renewables and storage are added to the grid, this will increase and is projected to reach over 80% by 2030, delivering reduced electricity costs.
Myth 3. Solar panels don’t work in high temperatures
Surprisingly this is a rather common misconception that is completely false. Solar panel efficiency is slightly reduced at elevated temperatures, but they never stop working at a specific temperature. The name-plate power rating of a solar panel, measured in Watts (W), is measured under controlled conditions at 25°C. However, in the real world, when a solar panel is exposed to sunshine, the temperature of the solar cells will rise to about 20°C above the ambient air temperature. So, on a 25°C deg day, the internal cell temperature could be closer to 45°C (depending on the wind and orientation of the panel). This, in turn, will reduce the cell efficiency resulting in a 6% to 10% reduction in power output. However, on a hot day above 40°C, a solar panel can reduce output by 12% to 20 % depending on the conditions, roof type, and wind speed. For example, on a hot day with little wind, a 450W solar panel will still generate around 380W, which isn’t an issue since most modern solar arrays are oversized to allow for losses.
The amount of power loss at high temperatures is determined by the ‘power temperature coefficient’. This is typically 0.35% per degree above 25°C. Panels built using the latest N-type monocrystalline cells are much more efficient in higher temperatures than older-generation polycrystalline cells. However, the best-performing panels in high temperatures use the more advanced IBC and HJT cells. Read more about these cell technologies in our solar panel efficiency article.
The opposite effect can occur when the air temperature is below 25 degrees, or if there is a very cold wind blowing across the panels. The cooling effect of low air-temperature and wind actually increases the performance of solar panels.
Myth 4. Solar panels don’t work when it’s cloudy
Like the clouds in question this one is a little grey. Solar panels will very rarely stop generating during cloudy weather and the reason is quite simple - clouds don’t completely block sunlight, otherwise it would be completely dark outside during bad weather.
The amount of solar energy generated during cloudy weather is reduced due to solar radiation being absorbed or reflected by the clouds. How much radiation passes through the clouds depends on the type of cloud and its density or thickness. Surprisingly, some high level thin cloud layers can scatter the sunlight which results in a slight increase in generation, especially during early morning and late afternoon.
During ‘normal’ cloudy weather the amount of solar generation is typically reduced by 60 to 80%, depending on the time of day and time of year. Summer is obviously much better than winter. However, during a thunderstorm or when clouds are very dark, the amount of solar radiation can be reduced to 5 or 10% compared to full sunshine, so the solar generation will be reduced accordingly.
In summary solar generation can be significantly reduced during cloudy weather but it varies depending on the type of cloud and time of day.
Myth 5. Solar panels will work during a blackout
Due to the strict safety requirements common grid-connected solar systems are required to shutdown during a grid outage or blackout. Blackouts often occur during severe storms when trees fall across power lines. To protect the emergency workers and service personnel fixing the damaged lines, all solar inverters must be automatically deactivated within 2 seconds of a blackout or a major grid voltage fluctuation being detected.
However, most ‘hybrid’ systems with battery storage are able to isolate from the grid during a blackout (called islanding) and provide some level of backup power. Generally, the amount of backup power is limited to lights and basic appliances, but several more advanced systems using multi-mode inverters are able to offer full backup power to most household appliances.
Myth 6. Solar panels use more energy to manufacture than they produce
Solar panels do not produce any emissions while in use, but they are made of different materials, including glass, aluminium, silicon and some plastics, which all require different levels of resources and energy. The energy used to extract, refine, transport and manufacture a product is known as the ‘embodied energy’. A typical solar panel will generate enough energy to repay the embodied energy within 3 to 4 years. However, as panel efficiency has increased significantly over the last few years, this has reduced to 2 to 2.5 years in many locations, especially regions with high average solar levels, such as Australia.
Close up of common silicon crystalline solar cells made mostly from high purity silica sand.
The energy payback time of solar panels is supported by multiple studies and life-cycle analysis (see references below). However, many detailed studies are now very outdated as solar cell efficiency has increased dramatically over the last few years. Due to increased efficiency and improved manufacturing methods, payback time for many modern systems can be as low as 18 months. Although, the additional emissions associated with the manufacture of the solar inverter and wiring can add another 6 to 10 months, pushing it back above 2 years. However, considering most solar panels will last 20-30 years, the system will repay the embodied energy multiple times over and offset thousands of tonnes of emissions.
Myth 7. Solar panels are toxic and can’t be recycled
Most claims of toxic solar panels come from obsolete thin-film or cadmium telluride (CdTe) solar panels. These older generation, less efficient panels were sold until around 2010, but quickly became obsolete due to the huge advancements in silicon crystalline solar cells, which were much more efficient and less expensive. Even so, Cadmium telluride (CdTe) panels contain less than 0.1% cadmium. Additionally, the compound of cadmium used in the cell is very stable and can be recaptured in recycling processes. Currently, over 99% of solar panels installed worldwide are the non-toxic silicon crystalline variety. It’s important to note that toxic elements are used in common consumer electronic devices, mobile phones, TVs and computers, which is why electronic or E-waste is a large global problem, as highlighted by the graphic below.
Almost all solar panels installed globally comprise of silicon crystalline PV cells encased in a polymer material and protected by a glass front and aluminium frame. There are virtually no toxic materials except for a trace amount of lead used in the solder. However, even the use of solder is being phased out with the new busbar compression joining techniques and conductive paste materials being used. REC is one of the leading solar companies that have eliminated the use of lead in all solder joints and connections. Other solar manufacturers are phasing out lead and using alternative solder compounds.
Chart from published Nature Physics research comparing the global cumulative waste streams from 2016 to 2050, to the relatively small volume of solar PV waste.
Research from Nature Physics shows that the amount of PV module waste expected from 2016 to 2050 is dwarfed by the huge volume of waste generated by coal ash and oil sludge from the fossil fuel industry. For example, coal ash waste is from 300 to 800 times greater than that from solar modules. Additionally, solar panel waste is already recyclable, with a rapidly expanding recycling industry developing around the world.
Recycling Solar Panels
Most solar panels installed over the last 20 years are still in use, so there is a relatively small amount of solar waste. However, over the next 10-20 years, many thousands of systems will reach the end of life (EOF), and there is expected to be a large increase in the volume of solar-related waste that will need to be recycled.
Solar panel recycling is an emerging industry, but due to the easily recycled materials such as the aluminium frames and mounting systems, there are many recycling facilities being built around the world. Most solar panel manufacturers are pushing to be more sustainable and are now part of the not-for-profit PV Cycle organisation - “PV CYCLE offers members and waste holders better access to take-back and ensure recycling rates above the industry standards.”
In Australia, there are several companies that will recycle old or damaged solar panels, including the Adelaide-based ReclaimPV. http://reclaimpv.com/
In Europe, the French waste management company Veolia has opened the first dedicated solar panel recycling facility in southern France, which is able to recover and recycle 95% of the materials.
For further reading here is a great article from RENEW about solar panel recycling.
Common solar panel construction using typical silicon crystalline solar cells made using silica sand.
References
Detailed life cycle analysis of solar PV systems
http://www.appropedia.org/LCA_of_silicon_PV_panels
http://iea-pvps.org/fileadmin/dam/public/report/technical/Future-PV-LCA-IEA-PVPS-Task-12-March-2015.pdf
https://www.researchgate.net/publication/264672000_Life_Cycle_Analysis_LCA_of_photovoltaic_panels_A_review
Manufacturing Silicon Wafers
https://sinovoltaics.com/solar-basics/solar-cell-production-from-silicon-wafer-to-cell/
https://pv-manufacturing.org/silicon-production/cz-monocrystalline-silicon-production/
Wholesale electricity price reduction
https://arena.gov.au/projects/peak-demand-reduction-using-solar-storage/
https://theconversation.com/wind-and-solar-cut-rather-than-boost-australias-wholesale-electricity-prices-119979
